1. Field of the Invention
The present invention relates to a method, of evaluating and correcting a robot program, for correcting an operation program of a robot so that the robot can perform a desired operation. The present invention also relates to a device for evaluating and correcting a robot program.
2. Description of the Related Art
In general, an operation program of a robot made off-line is seldom used at a work-site as it is but is only used after it has been corrected. The reason is that a relative positional relation between a workpiece and the robot is slightly different and, further, a posture of the robot is slightly different between the off-line state and the on-line state. In order to correct the operation program, a deviation of an operation route is corrected and, further, a speed command and an acceleration command to be given to a servo motor are corrected, in some cases.
In the case of correcting the speed command and the acceleration command of the operation program, a load given to the servo motor is checked. While a duty ratio is being checked with a teaching panel at a work-site, the speed command and the acceleration command are corrected. In this case, the duty ratio is a ratio of on-state to one operation cycle with respect to an electric current.
A deviation of the operation route is defined as a deviation between a target operation route and an actual operation route of a robot. In the case of correcting this deviation, with respect to a teaching point actually obtained when a target position of the workpiece is touched by the robot, a teaching point defined on an image plane is shifted so that the teaching point defined on the image plane can gradually approach the teaching point actually obtained when the target position of the workpiece is touched by the robot. In this way, the deviation is corrected so that the teaching point can be on the target operation route. An example of another method is described as follows. When a unit difference matrix, which is obtained from a difference between the teaching point of the target position and the teaching point actually touched, is multiplied by the target position from the its right side, the teaching point is shifted so that the teaching point can be corrected.
Examples of a well known device for evaluating and correcting a robot program are disclosed in the official gazettes of JP-A-2005-66797 and JP-A-2005-22062. Concerning the software to operate this type correcting device, “Roboguide” (registered trademark), which was proposed by the present applicant, is on the market.
However, the work which is conducted for correcting a speed command and an acceleration command to be given to the servo motor of the robot, while the duty ratio is being confirmed at the work-site, is accompanied by trial and error in many cases. Therefore, a large amount of labor is needed to conduct this work.
It is necessary to prudently conduct the work of correcting a deviation of the operation route at the work-site. Teaching points specified on the operation route, the deviations of which are large, must be touched and gradually shifted and corrected for each teaching point. Therefore, it can take a very long time to construct a manufacturing system in which the robot is used.